so you are in the middle of Barovia and hit lvl 9, how convenient that Count Strahd is around to knight you and give you what is yours by RAW
Isnt that much of a stretch that after 9 (a little low, I prefer those feature at level 11+) in Barovia, the fighter, the leader of man, the expert of the battle field, can muster a militia in one of the village or found a knightly order in an abandoned fort in the mountain? And after 20 level of battlefield expertise, call himself regent of a small settlement by offering the inhabitant is full, 20th level fighter, protection? Now, how that will work out between him and Strahd after gaining such things is another history, but that's the goal of a feature: creating an interesting history.
And should those things be impossible in your game, maybe just have them be big features in terms of roleplay yet small features in mechanical terms, so that they can be easily handwaved should the DM wishes to. Like the features that makes you un-aging and sustain yourself with you own mind, or thief's cant and druidic signs.
By the way, the game already has Temple of the God as a spell where I can erect a full-on magic temple to my deity in the middle of Barovia, no matter what the DM says (unless he vetoes it, but that's another thing: the DM can veto anything. The book cannot hold rules to replace any options the DM might veto!).
EDIT: Again, this is just one option that was discussed. But the others wont please you much more:
- Christmas Tree fighter: the fighter suddenly has new magic items at X levels.
- Demigod fighter: the fighter receives boon and blessing at higher level.
- Wuxia fighter: the fighter can break the physics of the setting at X level.
etc
Lets be honest: class features are already meta options for the players to veto the in-setting rules. The Lost Woods where people are lost forever? Not for this ranger! The impenetrable vault of the King of Greed? Not for this rogue with Stroke of Luck and expertise. The Great Desert of Thirst where even the water from your eyes seems to disappear? I can Create Water!
Now, again, a specific DM might have to deal with those because he dont like them, but the presence of said features doest not mean that the book enforce a ''give me that'' attitude from the players, as long as they are not an optional rules from a non-player book.